Escher: Add a ScrollViewIndicator

Change-Id: Ie619c16c9f784c3456a33de3ce21e25fae952ffc

escher/Makefile

@@ -5,6 +5,7 @@ objs += $(addprefix escher/src/,\
   childless_view.o\
   responder.o\
   scroll_view.o\
+  scroll_view_indicator.o\
   solid_color_view.o\
   tab_view.o\
   tab_view_cell.o\

escher/include/escher.h

@@ -3,6 +3,7 @@
 
 #include <escher/app.h>
 #include <escher/responder.h>
+#include <escher/scroll_view_indicator.h>
 #include <escher/solid_color_view.h>
 #include <escher/text_view.h>
 #include <escher/tab_view_controller.h>

escher/include/escher/scroll_view_indicator.h

@@ -0,0 +1,28 @@
+#ifndef ESCHER_SCROLL_VIEW_INDICATOR_H
+#define ESCHER_SCROLL_VIEW_INDICATOR_H
+
+#include <escher/childless_view.h>
+
+class ScrollViewIndicator : public ChildlessView {
+public:
+  enum class Direction {
+    Horizontal,
+    Vertical
+  };
+  ScrollViewIndicator(Direction direction);
+  void drawRect(KDRect rect) const override;
+
+  void setStart(float start);
+  void setEnd(float end);
+protected:
+#if ESCHER_VIEW_LOGGING
+  virtual const char * className() const override;
+  virtual void logAttributes(std::ostream &os) const override;
+#endif
+private:
+  Direction m_direction;
+  float m_start;
+  float m_end;
+};
+
+#endif

escher/src/scroll_view_indicator.cpp

@@ -0,0 +1,55 @@
+#include <escher/scroll_view_indicator.h>
+extern "C" {
+#include <assert.h>
+}
+
+constexpr KDColor k_backgroundColor = 0x00;
+constexpr KDColor k_indicatorColor = 0x30;
+
+ScrollViewIndicator::ScrollViewIndicator(ScrollViewIndicator::Direction direction) :
+  ChildlessView(),
+  m_direction(direction),
+  m_start(0),
+  m_end(0)
+{
+}
+
+void ScrollViewIndicator::drawRect(KDRect rect) const {
+  KDFillRect(bounds(), k_backgroundColor);
+  KDRect indicatorFrame;
+  if (m_direction == Direction::Horizontal) {
+  indicatorFrame.x = m_start*bounds().width;
+  indicatorFrame.y = 0;
+  indicatorFrame.width = (m_end-m_start)*bounds().width;
+  indicatorFrame.height = bounds().height;
+  } else {
+    assert(m_direction == Direction::Vertical);
+    indicatorFrame.x = 0;
+    indicatorFrame.y = m_start*bounds().height;
+    indicatorFrame.width = bounds().width;
+    indicatorFrame.height = (m_end-m_start)*bounds().height;
+  }
+  KDFillRect(indicatorFrame, k_indicatorColor);
+}
+
+void ScrollViewIndicator::setStart(float start) {
+  m_start = start;
+  redraw();
+}
+
+void ScrollViewIndicator::setEnd(float end) {
+  m_end = end;
+  redraw();
+}
+
+#if ESCHER_VIEW_LOGGING
+const char * ScrollViewIndicator::className() const {
+  return "ScrollViewIndicator";
+}
+
+void ScrollViewIndicator::logAttributes(std::ostream &os) const {
+  View::logAttributes(os);
+  os << " start=\"" << m_start << "\"";
+  os << " end=\"" << m_end << "\"";
+}
+#endif